Valve has done a pretty good job at standardizing VR tech with OpenVR/SteamVR. All of the headsets except the oculus seem to have really good hardware compatibility. The vive controllers can be used with the pimax hmd, etc.
Facebook seems to be trying really hard to create a lockin with the oculus, if you buy games on the oculus store, you are now forever locked in to only buying oculus hardware from now on.
Thankfully you can use Oculus devices (or at least, the Quest) with the new Link feature to turn the headset into a sort of external display, which is then compatible with SteamVR.
Honestly it's the biggest selling point of the Quest for me, in addition to being able to hack around on it through an adb shell.
Facebook seems to be trying really hard to create a lockin with the oculus, if you buy games on the oculus store, you are now forever locked in to only buying oculus hardware from now on.